In the prior art, there is a MEMS (Micro Electro Mechanical Systems) element in which minute electric elements and mechanical elements are installed on a one substrate by applying the micro-fabrication technology of the semiconductor manufacturing technology or laser processing technology or the like. As the MEMS element, there is an acceleration sensor, a pressure sensor or a gyroscope or the like.
Such a MEMS element is mounted on a wiring substrate, and a cap is provided on the MEMS element, thus the MEMS element is hermetically sealed in the package with a vacuum state. Since the MEMS element has the movable portion, it is necessary to mount and separate the movable portion from the wiring substrate such that the movable portion is in the free state. In the case that the MEMS element is mounted with an adhesive, the levelness can not be obtained sufficiently, and the vacuum airtightness is not enough due to the volatilization of the constituent in the adhesive.
A related art is disclosed in Japanese Laid-open Patent Publication No. 2006-179667.